On 10/7/2015 12:32 PM, Don Y wrote:
On 10/7/2015 10:04 AM, Muggles wrote:
On 10/7/2015 1:31 AM, Don Y wrote:

Some years ago, I posed what I thought was a (deceptively) "simple"
question regarding how we think of "local time" -- given that we
have control over our (individual) "timepieces".

E.g., my timepiece claims it is 11:25-ish. If I want to do something
at 12:00, that is ~35 minutes hence. So, I can think of it as being
tied to "12:00".

But, if I change my timepiece's notion of "now" to indicate 11:45,
what does that mean for that "12:00" event? Is it, suddenly, just
15 minutes hence? Or, is it really a 12:20 event, now?

I.e., how do you note which times (events) are "relative" (and, the
reference against which they relate) vs. "absolute"? How would the
answers to the above questions change if I'd said "If I want to do
something ~35 minutes hence" instead of "at 12:00"?

[It's a very subtle difference but has profound consequences when you
are instructing a machine to do something at a particular "time"...
esp given that *YOU* can change that machine's notion of the *current*
time!]

And, now it's "time for SOAP!" :

I husband set's the clock in his bathroom 10 mins ahead. He knows it's
set ahead of what it's supposed to be, but it's his way of giving
himself a buffer so he won't be late for appointments. He says when

Yes. But, the rame of reference that he's adopted is consistent
IN HIS MIND -- albeit "incorrect" for any other observer.

If charged with recording times of appointments and NOT allowed to
alter the setting of the local timepiece, he would probably opt
to record all of his *appointments* "ten minutes earlier" -- to
achieve a comparable effect.

Again, if *he* is the only one using that appointment book, all is
well.

He used to change my clock in my bathroom, and I changed it back! lol

But, if *I* have to fill in for him, some day, I'll find all of
those times *wrong*! And, not be sure *why* that's the case!
E.g., I showed up for his 7:50 appointment, but the other party
was 10 minutes late! And, this pattern continued throughout the
day! "Gee, he's sure working with a bunch of TARDY individuals!"

Is it a common practice for you to show up for someone elses appointments?

he's tired he just looks at the clock and uses that time to get ready
and temporarily forgets he set the clock ahead. It works for him, but
for me I'd want it set to the normal time. The thing about that is the
clocks at the place you have an appointment to be at may be set at a
different time (they may run ahead or behind), so, I've come to the
conclusion that time is actually "relative" to the environment and
people in that environment.

But it's actually worse than that! You not only have the time that
has been "recorded" and the time that is "currently displayed"
(both of which are "negotiable"... subject to manipulation by
the individuals involved) but you ALSO have the way the time was
originally *specified*!

E.g., if I throw some cookies in the oven for a 10 minute bake,
they must remain in the oven for 10 minutes. I can't glance at
the clock and mentally add 10 minutes to the time displayed -- *if*
someone can freely change the displayed time! (next time I look over
at the clock, it may not accurately reflect the ELAPSED time).

I'm not sure that's a really fair example. Who's going to be changing
the clock display while you're preparing cookies? OTOH, I understand
your point.

Similarly, if I have an appointment at 10:30A -- roughly 9 minutes
hence -- I don't want to "wait 9 minutes" because that displayed
time may, in fact, be incorrect! If it is corrected to indicate
the current time is actually 10:29, then I really only have *one*
minute to spare!

When you negotiate a time with someone else, then *their* notion
of time factors into the arrangement. And, their Role in The
Grand Scheme of Things.

Exactly.

I.e., set an appointment with a doctor and, chances are, their timepiece
will PROBABLY coincide with the "real" world time -- it would be
folly for them to set their timepiece 10 minutes fast/slow... or, even
to a different DATE! But, set an appointment with a friend and you
have no idea what their notion of time may be!

Agreed.

Is time the same in outer space, or is it different? We count time
based on particular increments related to the Earth's revolving around
the sun, so when the Sun and Earth are taken out of that equation how do
we know that time in outer space is measured the same? If the speed of

"How measured" is a local phenomenon. You can adopt any units that
are convenient for your local needs.

Time is just something that keeps everything from happening at once!
How finely you differentiate *this* once (instant) from *that* once
(other instant) depends on your needs.

Agreed.

light is a means to measure time, does it travel in a straight line in
outer space or travel by a curve, OR is the speed affected by the
gravitational pull from the different objects IN space and that
gravitational pull can either either speed up or slow down the speed of
light? How can we determine the age of objects in outer space if we
don't have a valid method of measuring time?

How can you know they even exist?

It makes for very interesting discussions especially when some people
insist on a particular viewpoint without even considering other
possibilities.

--
Maggie